With the evolution of wireless communication systems, users have increasingly high demands for high quality, high speed and new services. Wireless communication operators and equipment manufacturers need to constantly improve the system to meet the requirements of the users. It takes a lot of spectrum resources (which for example can be quantized with parameters such as time, frequency, bandwidth, and maximum allowable transmit power) to support new services and meet the needs of high-speed communications. Limited spectrum resources have been allocated to the fixed operators and services, and new available spectrums are either very scarce or expensive.
In this case, people propose the concept of dynamic spectrum utilization, i.e. the dynamic use of spectrum resources which have been assigned to some services but not yet fully utilized. For example, spectrums of a channel on which no program is delivered or spectrums of channels adjacent to the channel on the digital television broadcasting spectrum, are dynamically utilized to perform wireless mobile communication, without interfering with the reception of television signals. In this application example, since the television broadcasting spectrum itself is assigned to the television broadcasting system, the television broadcasting system is the primary system and the television is the primary user. In addition, the secondary system is a communication system which uses the spectrum resources of the primary system without interfering with the primary system, such as a wireless access point and wireless devices (such as computers, mobile phones) communicating with the wireless access point. The wireless access point is the manager of the secondary system, so the geographical position of the wireless access point represents the geographical position of the secondary system. Take another example, when a user uses a mobile phone to access the Internet and opens a hotspot function of the mobile phone so that the portable wireless devices, such as tablet computers, laptop computers, can access the Internet via the mobile phone, the position of the mobile phone represents the position of the secondary system. The primary system described herein can refer to a system which has the right to use a spectrum, such as a television broadcasting system; while the secondary system is a system which does not have the right to use the spectrum but can appropriately use the spectrum of the primary system only when the primary system does not use its own spectrum.
In addition, the primary system and the secondary system may be systems each having the right to use the spectrum but having different priority levels in the spectrum utilization. For example, when the operators deploy new base stations to provide new services, the existing base stations and the services provided by the existing base stations have the priority to use the spectrum. The primary system includes a primary user base station and primary users, while the secondary system includes a secondary user base station and secondary users. Communications between the secondary user base station and one or more secondary users or between multiple secondary users can constitute a secondary system. Multiple secondary systems in a certain region can be grouped into a secondary system cluster. For example, a secondary system cluster may include multiple wireless local area networks.
This communication in which the primary system and the secondary system coexist requires that the application of the secondary system should not cause interference to the application of the primary system, or that the impact caused by the spectrum utilization of the secondary system can be controlled within the allowable range of the primary system.
At present, a main way to protect the primary system is to store the coverage information of the primary system into a database. This database also stores interference limits that the primary system can tolerate. Before a secondary system in the same region starts to use the spectrum of a primary system in the same region, the secondary system firstly needs to access this database and submit the state information of the secondary system, such as position information, spectrum emission mask, transmission bandwidth, and carrier frequency. Then, the database calculates the amount of interference to the primary system from the secondary system according to the state information of the secondary system, and calculates the available spectrum resources of the secondary system in the current state according to the amount of interference to the primary system from the secondary system calculated in the current state.